The invention relates to a bearing system comprising two axially spaced hydrodynamic bearings by means of which two bodies, which comprise cooperating bearing surfaces between which a lubricant is present are supported for rotation about an axis of rotation relative to each other, at least one of the bearing surfaces of each of the bearings being formed with an inner pattern and an outer pattern of helical grooves, which two patterns of grooves act in opposite directions to build up a pressure in the lubricant between the bearing surfaces, during rotation of the bearing system in the direction for which the bearing System is intended, which bearing system further comprises a chamber which is situated between said hydrodynamic bearings, which serves as a reservoir for an additional amount of lubricant, and which is bounded by two cylindrical wall portions of said bodies.
Such a bearing system is known from U.S. Pat. No. 4,596,474 herewith incorporated by reference. The known bearing system is used in a construction comprising a rotatable cylindrical shaft and a stationary bearing housing. Between the two radial hydrodynamic bearings a gap is formed which functions as a reservoir for a spare amount of lubricant. The gap is situated between two concentric wall portions, one of the wall portions being a part of the shaft and the other wall portion being defined by an annular recess in the bearing housing. One of the two concentric wall portions is formed with two patterns of feed grooves for feeding lubricant towards the bearings during operation.
During rotation of the known bearing system in the direction for which the system is intended the lubricant in the bearings is massed up by the inner and outer patterns of grooves which cooperate as a fishbone pattern, to build-up pressure in the lubricant for a satisfactory hydrodynamic lubrication. In order to prevent this hydrodynamic action from being disturbed the bearings must always be provided with an adequate amount of lubricant, such as oil or grease. In the known bearing system this is achieved by providing an additional amount of lubricant in the gap between the bearings, from which gap the lubricant is pumped towards the bearings during operation.
In the known bearing system very small axial clearances between the two hydrodynamic bearings are not possible, because it is necessary that the feed grooves have a specific length for a correct operation of the patterns of feed grooves. A disadvantage of this is that the known bearing system cannot be used in constructions where the bearings must be closely spaced, for example in view of the available construction length.